r356087 made it rather innocuous to double-register built-in keyboard
drivers; we now set a flag to indicate that it's been registered and only
act once on a registration anyways. There is no misleading here, as the
follow-up kbd_delete_driver will actually remove the driver as needed now
that the linker set isn't also consulted after kbdinit.
Keyboard drivers are generally registered via linker set. In these cases,
they're also available as kmods which use KPI for registering/unregistering
keyboard drivers outside of the linker set.
For built-in modules, we still fire off MOD_LOAD and maybe even MOD_UNLOAD
if an error occurs, leading to registration via linker set and at MOD_LOAD
time.
This is a minor optimization at best, but it keeps the internal kbd driver
tidy as a future change will merge the linker set driver list into its
internal keyboard_drivers list via SYSINIT and simplify driver lookup by
removing the need to consult the linker set.
Most keyboard drivers are using the genkbd implementations as it is;
formally use them for any that aren't set and make
genkbd_get_fkeystr/genkbd_diag private.
A future change will provide default implementations for some of these where
it makes sense and most of them are already using the genkbd
implementation (e.g. get_fkeystr, diag).
These invocations were directly calling enkbd_diag(), rather than
indirection back through kbdd_diag/kbdsw. While they're functionally
equivent, invoking kbdd_diag where feasible (i.e. not in a diag
implementation) makes it easier to visually identify locking needs in these
other drivers.
Synthetic keyboard is the only supported keyboard on GEN2 Hyper-V.
Submitted by: Hongjiang Zhang <honzhan microsoft com>
MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D10196
